Automatically detecting the weight of the paper or other print media used in a printer, copier or other image forming device is desirable to help maintain good print quality. In laser printers and other electrophotographic image forming devices, the weight of the paper, as a discrete characteristic of the paper and as an indicator of paper thickness, is an important factor in determining the fusing temperature and pressure, the pick force necessary to feed each sheet into the printer, the speed at which the paper is advanced through the printer and the transfer current needed for good print quality. For example, heavier paper requires a greater pick force, higher fuser temperatures and pressures and often must be outputted face down to reduce curl.
Electrophotographic printers typically do not detect and automatically adjust for different weight papers. Some printers allow the operator to manually select a heavy paper setting in the computer printer driver or to adjust the fuser temperature on the printer control panel to maintain good print quality on heavy paper. Manual selection, however, is only effective if the operator is able to, and actually does, select the correct paper setting or fuser temperature. Manual selection is sometimes not practicable even for a knowledgeable and diligent operator, particularly when the paper is changed frequently among different weight and thickness papers and from several different input sources.